The broad goal of this study is to improve the treatment of boys with delayed puberty of clarifying the impact of androgen therapy on bone mineralization. The amount of skeletal mass acquired during adolescence and early adult life is one of the most important determinants of adult osteoporotic fracture risk. Androgen treatment in boys with delayed puberty is usually undertaken to alleviate psychological stress. However, it could have the potential of ameliorating the decreased bone mineral density (BMD) observed in adult men as a result of delayed puberty. If the aromatization of andogrens to estrogens during male puberty is required in order to increase the rate of bone accrual, the nonaromiatizable androgen, oxandrolone, will be less efficient in increasing bone mineralization than an equivalent dose of testosterone (T) in this critical period. This study is designed to investigate the relative effect of two accepted androgen therapeutic regimens on the rate of bone formation in delayed male puberty in an effort to define the hormonal mechanisms that drive the accumulation of bone mass during puberty.